It works like this:
Person A stands with their right hand in a loose fist. Person B places their open right hand RESTING GENTLY on top of (not hanging onto) Person A’s fist. Person B will then CLOSE THEIR EYES. With little children I would use a blindfold - they enjoy the experience, and they tend to have a hard time keeping their eyes closed on their own. Person A will lead the exercise by moving their fist all over the place, and the idea is for Person B to maintain contact with Person A’s fist at all times.
Don’t feel that you need to stay rooted to the spot and just move your hands – move around, take the other person on a journey around the room, up as high as you can both reach and down to the ground. Alternate quick movements and slow ones, sideways with up and down. Obviously be aware of furniture that you might knock into, and bonus if you can get out into a park where you have lots of space to move.
If you lose contact, simply pause for a second, find the other person, and carry on going. There is no specific time length to the exercise, but you’ll soon find that you’ll get tired enough to know its time for a break!
I use the right hand in the example, but you can obviously swap hands, and swap places as person A and B.
You’ll notice that as Person B, to maintain contact with Person A you need to be very anchored in the present moment. The minute you start thinking about something else, or getting stressed, or trying to anticipate the next move, you will lose your flow. Once you can become totally alert and focused and in the now, the exercise becomes simple and enjoyable and you should feel quite invigorated afterwards.